Respiratory System Flashcards
Organs of the respiratory system
- Nose
- Pharynx
- Larynx
- Trachea
- Bronchi
- Lungs alveoli
Functional anatomy of the respiratory system
- Gas exchanges between the blood and external environment occur only in the alveoli of the lungs
- Upper respiratory tract includes passageways from the nose to larynx
o Serve as a passageway for air moving in and out of the lungs
o Filter and remove foreign particles for inspired air
o Humidify and control temperature of inspired air
o Provide a sense of smell
o Assist with immune defence - Lower respiratory tract includes passageways from trachea to alveoli
o Passageways to the lungs purify, humidify, and warm the incoming air
o Gas exchange occurs at alveoli
Duties of the respiratory system
- Brain will cease to function, and death will occur if deprived of oxygen for 5-6 minutes
- Provides constant supply of O2 and removing C02 (waste product)
- Works cooperatively with the cardiovascular system to conduct gas exchange
o Collectively referred to as the cardiopulmonary system
o Blood pumped through acts as transport vehicle for O2 and C02
Explain features of the nose
- The only externally visible part of the respiratory system
o Nostrils (nares) are the route through which air enters the nose
o Nasal cavity is the interior of the nose
Deep to nostril is vestibular region
• Contains oily coated nasal hairs (cilia)
• Cilia trap and prevent particles from entering the nose
o Nasal septum divides the nasal cavity
- Olfactory receptors are located in the mucosa on the superior surface
o Provide sense of smell
- The rest of the cavity (respiratory cavity) is lined with respiratory mucosa, which
o Moistens air
o Traps incoming foreign particles
o Enzymes in the mucus destroy bacteria chemically
o Thin walls can cause nose bleeds
Explain duties and features of the conchae
- Conchae are projections from the lateral walls of the nasal cavity
o 3 projections (superior, middle, inferior)
o Increase surface area by creating 3 different passageways for filtering inspired air
o Increase air turbulence within the nasal cavity
o Increased trapping of inhaled particles by mucous membrane
Explain the palate (roof of the mouth)
- The palate separates the nasal cavity from the oral cavity
o Hard palate is anterior and supported by bone
o Soft palate is posterior, unsupported by bone, composed of soft tissue
Hanging from soft palate is the Uvula
• Small mass of CT and muscle fibres
• Believed to play a role in speech and helps prevent food from entering nasal cavity
Explain the duties and cavities of the paranasal sinuses
- Cavities within the frontal, sphenoid, ethmoid, and maxillary bones surrounding the nasal cavity
- Sinuses:
o Lighten the skull
o Act as resonance chambers for speech
o Produce mucus
o Warm and moisten inspired air
o Strengthen tone of the voice
Anatomical features of the pharynx
- Included in both respiratory and digestive systems
- Approximately 13 cm long
- Oropharynx (middle section) and laryngopharynx (lower section) serve as common passageway for air, food and liquid
o Epiglottis routes food into the posterior tube, the oesophagus - Pharyngotympanic tubes open into the nasopharynx (upper section)
o Drain the middle ear
o Due to this connection ear infection can cause an upper respiratory infection - Only air passes through the nasopharynx
What are the tonsils
- Tonsils are clusters of lymphatic tissue that play a role in protecting the body from infection
o Pharyngeal tonsil (adenoid), a single tonsil, is located in the nasopharynx
o Palatine tonsils (2) are located in the oropharynx at the end of the soft palate
o Lingual tonsils (2) are found at the base of the tongue
What is the function of larynx
- Commonly called the voice box
- Functions
o Routes air and food into proper channels
o Plays a role in speech - Triangular shaped and located inferior to the pharynx
- Made of eight rigid hyaline cartilaginous plates
o Thyroid cartilage (Adam’s apple) is the largest
What is anatomy and functions of epiglottis
- Found between the roof of the tongue and the larynx
- Spoon-shaped flap of elastic cartilage
- Protects the superior opening of the larynx
- Routes food to the posteriorly situated oesophagus and routes air toward the trachea
- During swallowing, the epiglottis rises and forms a lid over the opening of the larynx
o Prevents substance from entering the trachea
o If food or liquid enters trachea cough is triggered to expel substance before entering lungs
What are the vocal folds
- Located within the larynx
- Lined with a mucous membrane which folds to form the vocal cords
- True vocal cords
o Vibrate with expelled air
o Allow us to speak
What are the glottis
- Includes the vocal cords and the opening between the vocal cords
o Gives vocal cords room to vibrate to produce sound
Anatomical features of the trachea
- Commonly called the windpipe
- 4-inch-long tube that extends from the end of the larynx to the 5th Thoracic vertebrae
- Walls are reinforced with C-shaped rings of hyaline cartilage
o Anterior Rings - Contains rigid cartilage and prevents trachea from collapsing
o Posterior Rings - Do not contain cartilage, flexible, allow cartilage to expand - Lined with ciliated mucosa
o Cilia beat continuously in the opposite direction of incoming air
o Expel mucus loaded with dust and other debris away from lungs to larynx and pharynx
What is the main bronchi
- Formed by division of the trachea
- Each bronchus enters the lung at the hilum (medial depression)
- Right bronchus is wider, shorter, and straighter than left
- Bronchi subdivide into smaller and smaller branches
Main portions of the lungs
- Occupy the entire thoracic cavity except for the central mediastinum
- Apex of each lung is near the clavicle (superior portion)
- Base rests on the diaphragm
- Each lung is divided into lobes by fissures
o Left lung—two lobes (superior, inferior)
o Right lung—three lobes (superior, middle, inferior)
What are the pleura
- Serosa covers the outer surface of the lungs
o Pulmonary (visceral) pleura covers the lung surface and dips into fissures
o Parietal pleura lines the walls of the thoracic cavity
o Both secrete fluid which allows for gliding movements during respiration - Pleural fluid fills the area between layers
o Allows the lungs to glide over the thorax
o Decreases friction during breathing - Pleural space (between the layers) is more of a potential space
What is the bronchial tree
- Main bronchi subdivide into smaller and smaller branches
o Primary Bronchi Secondary Bronchi Tertiary Bronchi Bronchioles - Bronchial (respiratory) tree is the network of branching passageways
- All but the smallest passageways have reinforcing cartilage in the walls
- Bronchioles (smallest conducting passageways)
What are the respiratory zones
o Respiratory bronchioles
o Alveolar ducts
o Alveolar sacs
o Alveoli (air sacs)—the only site of gas exchange
Describe features of the alveoli
- Limited amount of gas exchange occurs in the respiratory bronchioles
- Main sites of gas exchange within the lungs
- Millions make up the bulk of the lung tissue
- Simple squamous epithelial cells largely compose the walls
- Alveolar pores connect neighbouring air sacs
- Pulmonary capillaries cover external surfaces of alveoli
Describe the air-blood barrier
- On one side of the membrane is air, and on the other side is blood flowing past
- Formed by alveolar and capillary walls
- Gas crosses the respiratory membrane by diffusion
o Oxygen diffuses across membrane of alveolar sac into the blood
o Carbon dioxide enters the alveoli sac from the blood ‘ - Gas exchange occurs rapidly because:
o Large surface area of the lung (unlimited number of sites for gas exchange)
o 02 and C02 only travel from RBC capillary wall/membrane alveolar wall/membrane
Membranes are very thin, thus allowing particles to move freely
o Gas always diffuses from area of high concentration to area of low concentration
C02 is high within the blood but low within lungs
02 is high within the alveolar sacs but low within blood - Alveolar walls are composed of very thin squamous epithelial cells
o Internal surface is coated by surfactant
Duty of the Alveolar macrophages
- Add protection by picking up bacteria, carbon particles, and other debris
Duty of the surfactant
- Coats gas-exposed alveolar surfaces
- Secreted by cuboidal surfactant-secreting cells
- Reduces tension in the alveoli and prevents them from collapsing
Functions of the respiratory system
o Supply the body with oxygen
o Dispose of carbon dioxide
Four events of respiration
o Pulmonary ventilation
o External respiration
o Respiratory gas transport
o Internal respiration
Pulmonary ventilation
- Mechanical process that depends on volume changes in the thoracic cavity
- Volume changes lead to pressure changes, which lead to the flow of gases to equalize pressure
- Boyles Law
o States that the volume of a gas is inversely proportional to its pressure
o At rest Both atmospheric and pressure within the lungs = 760 mm Hg
When equal lung volume does not change, therefore there is no airflow
o For lungs to take in air pressure within lungs must be less than the atmospheric pressure
o For lungs to expel air pressure within lungs must be greater than atmospheric pressure
2 phases of pulmonary ventilation
o Inspiration = inhalation
Flow of air into lungs
o Expiration = exhalation
Air leaving lungs
Impacts of inspiration
- External intercostal muscles contract
o Lifts ribs upward and outward
o Expand thoracic cavity - Diaphragm muscle contracts downwards and flattens
o Expand thoracic cavity - Intrapulmonary volume increases as lungs expand
- Gas pressure internally decreases
o While expanding pressure falls below atmospheric pressure thus creating a vacuum
Vacuum (sucking air into lungs) continues until intrapulmonary pressure equals atmospheric pressure
Describe expiration
- External intercostal muscles and diaphragm relax
o Decreases space within the thoracic cavity - Does not occur muscle contraction
o Normal expiration is a passive process
o When asthma or mucous accumulation restricts passageways or during exercise it becomes an active process
Forced expiration can occur mostly by contraction of internal intercostal muscles to depress the rib cage and expel air from the lungs
At the same time, abdominal muscles contract to push air out - Largely a passive process that depends on natural lung elasticity
- Intrapulmonary volume decreases
- Gas pressure increases to approximately 763 mm Hg
o When pressure exceeds atmospheric pressure air is expelled - Gases passively flow out to equalize the pressure
Describe intrapleural pressure
- The pressure within the pleural space) is always negative
- Major factor preventing lung collapse
- If intrapleural pressure equals atmospheric pressure, the lungs recoil and collapse
What factors affect respiratory capacity and what volume can they hold
o Size o Sex o Age o Physical condition healthy adult lungs = 6 L of air
What is the tidal volume (TV)
o Normal quiet breathing
o 500 ml of air is moved in/out of lungs with each breath
o Volume of air inhaled within a normal breath
Static lung volume
- Measures only volumes
- Can be used to determine whether a deficiency or disorder exists
- A person performs a series of breathing manoeuvres
o Initially, person is told to breathe normally for at least 6 breaths (provides measure of tidal volume)
o Then, person breathes in as deeply as possible to measure the IRV
o They then breathe out as deeply as possible to measure ERV
o By adding together, the TV, IRV and ERV the Vital Capacity can be calculated
Inspiratory reserve volume (IRV)
- Amount of air that can be taken in forcibly over the tidal volume
- Usually around 3,100 ml
Expiratory Reserve Volume
- Amount of air that can be forcibly exhaled after a tidal expiration
- Approximately 1,200 ml
What is the residual volume
- Air remaining in lung after expiration cannot be voluntarily exhaled
- Allows gas exchange to go on continuously, even between breaths, and helps keep alveoli open (inflated)
- About 1,200 ml
- By adding together, the Vital Capacity and the Residual Volume
o Total lung capacity can be found
Vital capacity
- The total amount of exchangeable air
- Vital capacity = TV + IRV + ERV
- 4,800 ml in men; 3,100 ml in women
Dead space volume
- Air that remains in conducting zone and never reaches alveoli
- About 150 ml during normal tidal breath
Functional Volume
- Air that actually reaches the respiratory zone and contributes to gas exchange
- Usually about 350 ml
- Respiratory capacities are measured with a spirometer
Examples of of non-respiratory Air movements
o Cough and sneeze—clears lungs of debris and dust from lower respiratory tracts and upper respiratory tracts
o Crying—emotionally induced mechanism
o Laughing—similar to crying, emotionally induced
o Hiccup—sudden inspirations, irritation of the phrenic nerves to cause the diaphragm muscle to spasm
o Yawn—very deep inspiration, need for increased oxygen in the lungs
Gas exchange through diffusion examples
o External respiration is an exchange of gases occurring between the alveoli and pulmonary blood (pulmonary gas exchange)
o Internal respiration is an exchange of gases occurring between the blood and tissue cells (systemic capillary gas exchange)
External Respiration
- Oxygen is loaded into the blood
o Oxygen diffuses from the oxygen-rich air of the alveoli to the oxygen-poor blood of the pulmonary capillaries
o Always more oxygen within the alveoli than the blood - Carbon dioxide is unloaded out of the blood
o Carbon dioxide diffuses from the blood of the pulmonary capillaries to the alveoli and be flushed out of the lungs during expiration - Dark-red, deoxygenated blood flowing through the pulmonary circuit bright-red oxygenated blood flowing through the systemic circuit to the heart
Oxygen transport in the blood
o Most oxygen travels attached to hemoglobin molecules and forms oxyhemoglobin (HbO2 )
o A small, dissolved amount is carried in the plasma
CO2 transport in the blood
o C02 is 20x more soluble than 02
Most carbon dioxide is transported in the plasma as bicarbonate ion (HCO3 – )
• Important at buffering the blood pH
C02 is enzymatically converted to bicarbonate ion within the RBC’s
• Newly formed HCO3- diffuse into the plasma
• A small amount is carried inside red blood cells on hemoglobin, but at different binding sites from those of oxygen
CO2 diffusion requirements
o It must be released from its bicarbonate form:
Bicarbonate ions enter RBC
Combine with hydrogen ions
Form carbonic acid (H2CO3 )
Carbonic acid splits to form water + CO2
Carbon dioxide diffuses from blood into alveoli
Internal Respiration
- Exchange of gases between blood and tissue cells
- An opposite reaction from what occurs in the lungs
o Carbon dioxide diffuses out of tissue cells to blood (called loading)
In blood, C02 binds with water to form carbonic acid quickly releases HCO3-
Most of the conversion from carbonic ions to bicarbonate ions occurs inside RBC’s
Bicarbonate ions diffuse out into plasma then transported
o Oxygen diffuses from blood into tissue (called unloading)
02 is released from Haemoglobin to enter cells - As a result of these exchanges
o Venous blood in systemic circulation is much poorer in oxygen and richer in carbon dioxide than blood leaving the lungs
Neural centers that control rate and depth
Medulla
• Sets basic rhythm of breathing and contains a pacemaker (self-exciting inspiratory center) called the ventral respiratory group (VRG)
• Inspiration Centre stimulates the diaphragm and intercostal muscles
o Achieved by efferent nerve impulses sent through the phrenic and intercostal nerves
o As lungs fill with air stretch receptors in the bronchioles and alveoli prevent over inflation of alveolar sacs
o Send nerve impulses to medulla via the vagus nerve to start exhalation
Pons
• Smoothes out respiratory rate
• Coordinates transition from inspiration to expiration
Physical factors influencing respiratory rate and depth
Increased body temperature
Exercise
Talking
Coughing
Volition influencing respiratory rate and depth
During singing and swallowing breath control is important
Many have held breath underwater to swim
Limited and respiratory centres will ignore attempts to control breathing when 02 supply in blood is low or blood pH is falling
Emotional factors influencing respiratory rate and depth
Fear, anger, and excitement
Panting when frightened result from emotional stimulus acting through centres in the hypothalamus
Impact of CO2 levels on respiratory rate and depth
Central chemoreceptors constantly monitor changes in cerebrospinal fluid pH
• Decrease indicates high level of C02 within body
• When detected stimulate the brains inspiratory centre by sending impulses via the vagus and glossopharyngeal nerves
• Inspiratory centre increases the rate and depth of breathing
• Result is a fresh supply of oxygen and lowered C02 levels
When metabolism increases oxygen consumption increases, and body produces more C02
The body’s need to rid itself of CO2
• Only chemical which can cross the blood brain barrier
Increased levels of carbon dioxide (and thus, a decreased or acidic pH) in the blood increase the rate and depth of breathing
• Also lead to more hydrogen ions in the body cause pH of CSF to decrease
Changes in carbon dioxide act directly on the medulla oblongata
C02 is the main chemical driving force behind respiration
Impact of oxygen levels on respiratory rate and depth
Changes in oxygen concentration in the blood are detected by peripheral chemoreceptors in the aorta and common carotid artery
• Also, mildly sensitive to changes in the C02
Information is sent to the medulla
Hyperventilation
- Rising levels of CO2 in the blood (acidosis) result in faster, deeper breathing
- Exhale more CO2 to elevate blood pH
- May result in apnea and dizziness and lead to alkalosis
Hypoventilation
- Results when blood becomes alkaline (alkalosis)
- Extremely slow or shallow breathing
- Allows CO2 to accumulate in the blood
Normal respiratory rate
eupnoea
o 12 to 15 respirations per minute
Hyperpnea
o Increased respiratory rate, often due to extra oxygen needs (e.g., when exercising)
Apnoea
o Cessation of breathing
- Chronic obstructive pulmonary disease (COPD)
o Exemplified by chronic bronchitis and emphysema
o Shared features of these diseases
Patients almost always have a history of smoking
Labored breathing (dyspnea) becomes progressively worse
Coughing and frequent pulmonary infections are common
Most COPD patients are hypoxic, retain carbon dioxide and have respiratory acidosis, and ultimately develop respiratory failure
Chronic Bronchitis
o Mucosa of the lower respiratory passages becomes severely inflamed
o Excessive mucus production impairs ventilation and gas exchange
o Patients become cyanotic and are sometimes called “blue bloaters” as a result of chronic hypoxia and carbon dioxide retention
Emphysema
o Alveoli walls are destroyed; remaining alveoli enlarge
o Chronic inflammation promotes lung fibrosis, and lungs lose elasticity
o Patients use a large amount of energy to exhale; some air remains in the lungs
o Sufferers are often called “pink puffers” because oxygen exchange is efficient
o Overinflation of the lungs leads to a permanently expanded barrel chest
o Cyanosis appears late in the disease
Lung cancer
o Leading cause of cancer death for men and women
o Nearly 90 percent of cases result from smoking
o Aggressive cancer that metastasizes rapidly
o Three common types
Adenocarcinoma
Squamous cell carcinoma
Small cell carcinoma
